Today's headpieces, which are equipped with a pneumatic system for sucking up the shavings that are produced during machining, move continuously, pressing from time to time on the area of the board to be machined where a hole is to be made.
The total amount of time that it takes to make a single hole therefore consists of the time that it takes the headpiece to reach the board starting from an initial standby position and the time it takes the headpiece to retract. The time required for the drilling per se therefore lies within this interval and is shorter than the latter, since the tip rests on the board to be drilled only after the headpiece has finished being compressed against an elastic packing with which it is equipped; this packing has to be used in order to avoid damaging the board itself and to ensure that uniform pressure is exerted on said board over the entire contact surface.
The two lengths of time, elastic compression and elastic reexpansion of said packing, are therefore dead times that are added to the time that the drilling work itself takes.
In the more common case mentioned above, where machining is done on printed circuit boards, the work of drilling, which involves advancing a few millimeters in a fairly friable material, lasts an extremely short time for each individual hole, and therefore the dead times involving the actual actuation of the headpiece increase substantially in terms of percentage.